Portable radios may include optional accessories such as external speakers or microphones. For convenience it is desirable for such portable radios to automatically adjust their mode of operation to the option connected to it. Typical connectors for external accessories include various pins for making the electrical connections between the portable radio and the accessory. Due to the limited space available in a portable radio the number of pins used for providing the required connections is limited. Therefore, a need exists for an option selection apparatus that uses the pins of the connector efficiently.